1. Field of the Invention
The present invention relates in general to a rotary switch and more particularly to a sealed rotary switch which is to be used in a severe environment.
2. Description of the Prior Art
Hitherto, various kinds of rotary switches have been proposed and put into practical use particularly in the fields of motor vehicles, construction machinery and other industrial machines.
Some of the conventional rotary switches are of a type which uses a micro-switch as means for producing information signals, viz., ON-OFF signals. As is known, the micro-switch is of a small and highly sensitive switch in which minute and feeble motion establishes contact. However, due to this inherency, the microswitch sometimes suffers from malfunction particularly when it is used in a very cold environment.
In order to clarify this undesired matter, one of the conventional rotary switches of the above-mentioned type will be outlined with reference to FIG. 10.
The conventional rotary switch "B" illustrated in the drawing comprises a micro-switch "A" having an actuator button "E" and an actuator arm "D", and a rotary cam "C" having a shaped periphery to which a leading end of the actuator arm "D" slidably contacts. The actuator button "E" is biased outwardly by a suitable biasing means housed in the micro-switch "A", so that the leading end of the actuator arm "D" is pressed against the periphery of the rotary cam "C". Upon rotation of the rotary cam "C" about its axis, the leading end of the actuator arm "D" slides on and along the periphery of the rotary cam "C" while intermittently pushing the actuator button "E" in accordance with the shape of the rotary cam "C". Usually, the biasing force applied to the actuator button "E" by the biasing means is set to such a relatively small degree as to barely push back the actuator arm "D" when the latter comes to a depressed OFF position of the periphery of the rotary cam "C". Thus, when, for example in winter, some parts of the micro-switch "A" are iced even weakly, it tends to occur that the actuator button "E" fails to closely follow the swinging movement of the actuator arm "D" thereby causing malfunction of the micro-switch "A", viz., malfunction of the rotary switch "B".